This is a pharmacologic and toxicologic study of the use of an antiepileptic medication which is widely used outside the United States. This medication has demonstrated to be a very safe and effective antiepileptic agent in other countries but adequate U.S. studies have not been completed. This study involves evaluation of patients for toxicity including all standard blood tests, plus tests of hearing, visual function, EKGs and EEGs. Pharmacologic studies of valproate include determinations of the therapeutic dose range, the half-life, the volume of distribution, the time to steady state, and the effect on other antiepileptic drugs. Evaluation of the efficacy of this drug is carried out by intensive monitoring techniques including video tape seizures with simultaneous electroencephalographic recording, long-termed telemetered EEG recording and frequent determination of antiepileptic drug concentrations. BIBLIOGRAPHIC REFERENCES: Penry, J.K., Porter, R.J., Sato, S., Reddenbough, J., Dreifuss, F.E.: Effect of Sodium Valproate on Generalized Spike-wave Paroxysms in the Electroencephalogram. In Legg, N.J. (Ed.): Clinical and Pharmacological Aspects of Sodium Valproate (Epilim) in the Treatment of Epilepsy. Proceedings of a Symposium Held at Nottingham University, September 23-24, 1975. Tunbridge Wells, England, MCS Consultants, 1976, 158-164.